[chef-dev] Ohai Ruby plugin: system ruby vs. running ruby?

[Daniel DeLeo < >]

 Ohai Chefs, we'd like to get your feedback on an issue that's been reported 
a few times for ohai[1]. 

The problem is that ohai shells out to the `ruby` executable in order to 
populate the languages/ruby attributes. 

This is good because:

* It detects the "system" ruby even if you have several rubies installed, or 
are running Chef with a different ruby (i.e., running chef under REE or 
whatever). This is consistent with the other language plugins which detect 
`python` (but not python26) `java`, and so on. It's not consistent with the C 
plugin which will detect all of GCC, MS, IBM, Sun, and HP-UX compilers.

This is bad because:

* It detects a different ruby than the one you're using for Chef.
* It does not detect a ruby installed as `ruby18` or `ruby19` (or rbx or 
jruby for that matter)
* It's slower than using rbconfig within the same ruby process.

There's a few things we could do about this:
1. Always use the Ruby that you're using for ohai/chef-client. If we do this, 
we could avoid shelling out entirely and the ruby plugin would run faster.
2. Try to run `ruby18` or `ruby19` (and/or `rbx`, `jruby`, etc.) if there is 
no `ruby` in the PATH.
3. Do the same as #2, but try to find every Ruby we can, e.g., detect *all* 
of ruby, ruby18, ruby19, rbx, jruby.

To be honest, I'm not sure what people are using the languages/ruby 
attributes for, so I'm not able to make a judgement about which of these 
options is best (or maybe there's another option?). If this is something that 
matters to you, please chime in and explain your use case and which course of 
action would be most helpful to you.

Thanks!

-- 
Dan DeLeo

1. http://tickets.opscode.com/browse/OHAI-172 is the canonical ticket, there ;
are some duplicates as well.